Hi Antero.
I might be able to help with some of your questions.
First, your guitar was most likely built by Kawai. They produced a million variations on their guitars so it is not surprising you haven't found an exact match for your guitar. Most guitars produced by Kawai had no factory model designation. Sometimes a distributor would attach a model name but generally these were just descriptive.
Based on the tailpiece and bridge, I'd say your guitar was built around 1969.
The bridge is made with round saddles so the strings will move more freely when using the whammy bar.
EZPZ has an accurate whammy bar. I've purchased several bars from them. They make high quality reproductions and have great customer service. Here the link:
The pickups are single coils. This style came in both black and white covers. I think the black ones were generally earlier but I'm not sure about this. Maybe someone else has worked out when Kawai used different styles of pups.
The guitar has a few issues that will effect value. It looks like one of the knobs is broken but that can be fairly easily replaced. It is missing the string retainer bar which you can buy on eBay once you get a proper width measurement. If the tuners are not in good shape that will reduce value as well. The scratch marks around the tuners don't help value. On the plus side, although the basic style of the guitar is fairly common, I don't see the 4 pickup versions very often.
I'm not sure about prices in Portugal but in the US something between $200-$300USD would be a reasonable expectation.